The present invention concerns a receptacle, normally in a vacuumized state, for the selective taking of gas or air samples for forensic evaluation.
In the investigation of events, such as explosions or accidents involving a gas, samples taken are helpful in determining cause and/or origin. The use of stored vacuumized receptacles opened at a site for the intake of ambient air or gas samples has been proposed but to be practical requires that sample taking must occur promptly after the event. In the instance of an explosion chemical analysis of a sample can help in the determination of the explosive type and origin. Similarly, the timely collection of any airborne particulate at a site may be helpful.
It would be desirable to have a number of vacuumized containers stored at selected sites to permit rapid delivery to a leak, spill or explosion site. Heretofore, the maintenance of a vacuumized state in stored containers has proved difficult in view of known valve designs permitting some leakage.
U.S. Pat. No. 3,618,393 discloses a vacuum tank with an inlet controlled by a manually operated valve.
U.S. Pat. No. 4,040,299 discloses a vacuum tank provided with a vacuum controlling valve and an inlet controlling second valve, a vacuum gauge and a filter located at the inlet end of a tubular inlet. A gas sample is drawn from a vacuum tank via a self-sealing septum, as is the case with many prior art vacuum receptacles.
U.S. Pat. No. 6,073,648 discloses a ball valve for use in highly corrosive and highly erosive environments. Wetted surfaces 24a of the valve body and wetted surface 28a of the ball component are firstly coated with a noble metal and secondly with a ceramic material, which per Col 3., Lines 58-63, is conceded to be porous and hence the patented valve does not address the problem solved by the present invention, i.e., sealing a vacuumized receptacle against atmospheric pressure over a period of several months and perhaps years.